FUNGUS DISEASES 95 



tion of these three diseases was made. A fourth disease, 

 found in neglected cultivations and known locally as 

 "saltpetre" and "black-head," has been determined by 

 the Mycologist of Jamaica to be the well-known pine- 

 apple disease of the sugar-cane (Thielaviopsis ethaceticus) ; 

 but this disease is not considered dangerous, if remedial 

 measures be promptly taken. 



It is supposed that the Surinam Panama disease had 

 been present in Jamaica for five years, and possibly for 

 eight or ten years, and yet only 5 per cent, of the plants 

 on the infected area were diseased. The inference drawn 

 by the Director of Agriculture is that the conditions in 

 Jamaica favour a strong constitution in the plants, making 

 them almost immune from this disease. 



Under the Infectious Diseases Law * no one is allowed to 

 grow diseased bananas or other economic plants which 

 may spread disease to his neighbours. Any person having 

 reason to believe that disease exists in land neighbouring 

 to his own, may notify the person in charge to carry out 

 the treatment prescribed under the law ; if no attention 

 is paid to this, the matter is reported to an inspector. 

 Inspectors may inspect plants suspected to be diseased, 

 and are empowered to carry out the treatment prescribed 

 at the cost of the owners ; if it is impossible to cure the 

 disease, the plants are to be cut down and burnt. 



2. ROOT DESTRUCTION BY FUNGUS MYCELIA| 



(1) Stone Fungus. The soil of banana cultivations in 

 Australia is occasionally found to be compacted in irregu- 

 larly shaped masses that have an almost stone-like density. 

 These masses are due to the mycelium of a fungus filling 

 every interstice of that portion of soil, and enclosing root- 

 fibres and other bodies. The outer surfaces of these masses 

 are defined by a thin, dense, almost black layer, principally 

 formed by iron that the organic matter present, in the 



* Journ. Jam. Agric. Soc., xv. 405 (1911). 



f H. Tryon in Queensland Agric. Journ., xxviii. 284 (1912). 



